Okay I have found a generic KStN for a POW camp of 30,000 PWs that has a medical staff like that posted above. So assuming a similar organizational structure for a Frontstalag in Occupied France then it would be somewhat underutilized as Bordeaux only held about 10,000 and the Rennes extension (221 W) only had about 700 wounded PWs at a time.
There was a Lazarett 133 which held about 8,000 Colonial PWs which was divided into a Dulag sort of arrangement in June 1944 to handle Allied PWs which the PWs refered to as Stalag 221 or Stalag 123 and the old section with the Colonial PWs. The Colonial PWs used to throw food over the wire to the Allied PWs because the Allied PWs weren't getting even a half ration plus the Colonials got Red Cross parcels as well. This may have accounted for the some of the unused capacity.
There was 1 German and 1 French doctor in the Dulag. So that would leave 1 doctor in Bordeaux (221 S), with 2 at the Rennes Hospital (221 W) and 1 at the Dulag (221?). This would account for all 4 doctors in the KStN excusing a lot of assumptions.
LTC USA (Retired)